Sr

Electro Discharge Machining Processes are used only when no other traditional machining process, like drilling, milling, grinding and other traditional machining operation can meet the necessary requirements efficiently and economically. Electro discharge machining is a non-traditional

Dry EDM is an environment-friendly modification of the oil based EDM process. In the current work, a unit has been developed to implement dry EDM process on existing oil based EDM machine. All experiments are performed on bright mild steel with the help of hollow copper electrode. Response variables analyzed are material removal rate, tool wear rate and surface roughness. Design of experiments is done using Taguchi method. All experiments are performed using process parameters such as current, pulse on time and oxygen gas pressure. The statistical analysis of results show that current and POT significantly influence MRR and TWR.

FtsY, the Escherichia coli homologue of the eukaryotic SRP receptor (SRα), is located both in the cytoplasm and in the inner membrane of E. coli. Similar to SRα, FtsY consists of two major domains: a strongly acidic N-terminal domain (A) and a C-terminal GTP binding domain (NG) of which the crystal structure has recently been determined. The domains were expressed

The development of new materials shows the immense growth but the major problem, it is very difficult to machine the newly developed materials. So it is necessary to adopt some new machining methods. Electrical Discharge Machining (EDM) is a non-traditional and most popular machining method to manufacture dies, punches and press tools because of its capability to produce complicated, intricate shapes and to machine hard materials. Electrical Discharge Machining performance is generally evaluated on the basis of Overcut (OC), Material Removal Rate (MRR), Tool Wear Rate (TWR) and Surface Roughness (SR). The important EDM machining parameters affecting to the performance measures of the process are discharge current, pulse on time, pulse off time, arc gap, and duty cycle. Several approaches are proposed in the literature to solve the problems related with optimization of these parameters. It is felt that a review of the various approaches developed would help to compare their main features and their relative advantages or limitations to allow choose the most suitable approach for a particular application and also throw light on aspects that needs further attention. In view of above, this paper presents a review of Effect of Electrode Material on Overcut, MRR, TWR of Steel Material in EDM.

Strontium isotopes are a powerful tool for investigating
the geographical origins of people and animals
but assignment of provenance requires reference
maps and databases. This paper presents a map of
strontium isotope variations across Britain for use in archaeological and other studies, and is produced by direct measurement of strontium isotope compositions of biosphere
components, predominantly plants. The map characterizes
the biosphere signature of specific lithologies: a technique
that is applicable worldwide. Marine-derived strontium, from
both rainwater and coastal sea-splash and spray, is an
important contribution to the British biosphere, particularly
on the western seaboard, which is subject to high rainfall and
prevailing westerly winds.

This paper concerned with study the effect of a graphite micro powder mixed in the kerosene dielectric fluid during powder mixing electric discharge machining (PMEDM) of high carbon high chromium AISI D2 steel. The type of electrode (copper and graphite), the pulse are taken as the process main input parameters. The material removal rate MRR, the tool wear ratio TWR and the work piece surface roughness (SR) are taken as output parameters to planned using response surface methodology (RSM) design procedure. Empirical models are developed for MRR, TWR and SR, using the analysis of variance (ANOVA).The best results for the productivity of the when using the graphite electrodes, the pulse current (22 A), the pulse on duration (120 µs) and using the graphite powder mixing in kerosene dielectric reaches (82.84mm³/min). The result gives an improvement in material removal rate of (274%) with respect to the corresponding value obtained when copper electrodes with kerosene dielectric alone. The best results for the tool wear ratio (TWR) of the process obtained when using the copper electrodes, the pulse current (8 A), the pulse on duration (120 µs) and using the kerosene dielectric alone reaches (0.31 %). The use of graphite electrodes, the kerosene dielectric with 5g/l graphite powder mixing, the pulse current (8 A), the pulse on duration (40 µs) give the best surface roughness (141%) with respect to the corresponding value obtained when using copper electrodes and the kerosene dielectric alone with the same other parameters and machining conditions.

The islands of Alor, Lirang, Wetar and Romang are located in the extinct section of the Sunda–Banda arc, where the collision with the Australian continent has brought subduction to a halt. Intrusive and extrusive igneous samples show a wide range of Sr, Nd and Pb isotopic characteristics. Samples from the northeast coast of Alor extend the trend of increasing 206Pb/204Pb ratios along the arc in an easterly direction, with values as high as 19.6. Samples from Alor's south coast, Lirang, Wetar and Romang have appreciably lower 206Pb/204Pb ratios (≤19.1), and 143Nd/144Nd ratios down to 0.5119. The Pb isotope data are interpreted as reflecting mixing between two internally variable end members within the subducting Australian continent, either the upper and lower crust, or two upper crustal end members of different ages. These melts may come up virtually unmodified, giving rise to the felsic, low 143Nd/144Nd samples, or may interact with the mantle, of which the partial melts and the fractionation products thereof give rise to basalts to rhyodacites with more intermediate Nd isotopic characteristics. Mixing modelling of the latter samples' isotopic ratios constrains the amount of crustal material that has been added to the mantle wedge to reach up to 9%. The isotopic and trace element heterogeneity in the samples studied is likely to reflect inhomogeneity of the crustal sources contributing to magmatism.

Sixteen short sediment cores were recovered from the upper edge (UEO), within (WO) and below (BO) the oxygen minimum zone (OMZ) off Peru during cruise 147 of R/V Sonne. Solids were analyzed for major/trace elements, total organic carbon, total inorganic carbon, total sulfur, the stable sulfur isotope composition (δ34S) of pyrite, and sulfate reduction rates (SRR). Pore waters were analyzed

Right ventricular apical pacing may induce detrimental effects on left ventricular function and coronary flow. In this study, the effects of pacing site and mode on cardiac mechanics and coronary blood flow were evaluated. This prospective study included 25 patients who received dual-chamber pacemakers with the ventricular lead placed in the right ventricular apex and presented in sinus rhythm (SR) at their regularly scheduled visits at the pacemaker clinic. Patients underwent complete transthoracic echocardiographic examinations while in SR, followed by noninvasive Doppler assessment of coronary flow in the left anterior descending coronary artery (LAD) and speckle-tracking echocardiography of short-axis planes in SR, atrial pacing (AAI-P), atrioventricular (dual-chamber) pacing (DDD-P), and ventricular pacing (VVI-P). Rotation of the base was significantly decreased with VVI-P compared with AAI-P. Left ventricular twist decreased significantly with DDD-P compared with AAI-P. Circu...

Electrical discharge machining (EDM) is non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and a tool electrode. A pulse discharge occurs in a small gap between the work piece and the tool electrode and removes the unwanted material from the material through melting and vaporizing. The present study discusses about having an overview of the Electrical discharge machining process, and influence of process parameters like input current, pulse on time and pulse off time on performance parameter such as MRR, EWR and over cut. This study discusses about controlling the process parameters and optimization of process parameters in EDM process. From the review, it has been observed that the machining process can be improved by process parameters like current, pulse on time and pulse off time and also observed that electrodes material also effect on the material removal rate, electrode wear rate and over cut.

In patients with heart failure, left ventricular ejection fraction ≤35% and sinus rhythm without conditions such as atrial fibrillation, thrombus or history of thromboembolic events, the use of anticoagulation is controversial. Our objective was to evaluate the anticoagulation strategy in these patients, variables associated with its use, and its effects on various cardiovascular events. Of the patients included in the REDINSCOR registry with left ventricular ejection fraction ≤35% and sinus rhythm without other anticoagulation indications (including patients with heart failure from 19 Spanish centres), we compared those who received this treatment with the remaining patients. Between 2007 and 2010, 2263 patients were included, of whom 902 had left ventricular ejection fraction ≤35% and sinus rhythm. Of these, 237 (26%) were receiving anticoagulation therapy. Variables associated with this treatment were a lower left ventricular ejection fraction, ischemic etiology, advanced functio...